Hydraulic Design

StormPRO® and SewerPRO® pipes are normally sized to accommodate maximum design discharge when flowing full. The discharge rates in the Tables below for StormPRO® and SewerPRO® pipes flowing full are based on the Colebrook-White formula which is recognised by engineers throughout the world as the most accurate basis for hydraulic design over a wide range of flow conditions.

In addition to friction losses in the pipeline, a pressure drop will occur due to energy loss at any change in the direction of flow or pipeline cross section. In long pipelines, these “form losses” are usually small in comparison to friction losses. However, they may be considerable in pipelines with many fittings or in short pipes such as in culvert applications, where entry and exit losses may dominate. For more information on form losses, consult the Vinidex Flow Charts.

Choice of Roughness Coefficients

AS 2200 – Design charts for water supply and sewerage – recommends k values in the range 0.003 to 0.015mm for clean, concentrically jointed thermoplastics pipes and AS 3500.3 – National plumbing and drainage, Part 3 Stormwater drainage – specifies 0.015mm for design of plastics stormwater pipe drains for normal conditions.

However, it is important to note that factors such as slime growth and accumulation of debris can affect the selection of roughness coefficient in some circumstances. In addition, local utilities may have preferred values for design of their systems. For flow under alternative conditions contact Vinidex or use the Vinidex Friction Loss in Uniform Fluid Flow software.